| Private cloud is popular among enterprises due to its advantages of security and high service quality.It is a service model of cloud computing.In today's society where hardware and software are increasingly updated and terminal devices are constantly being replaced,storing data in the cloud will bring great convenience.People only need to install a cloud client on the terminal,and they can use cloud resources without updating too much software.The VNC(Virtual Network Computing)protocol is a bridge between the terminal device and the private cloud.When users use a private cloud desktop environment for office work,they use the VNC protocol to transmit messages such as images,mouse,and keyboard.Cloud resources can be operated remotely.VNC's image transmission uses the RFB(Remote Frame Buffer)protocol.The RFB protocol works at the frame buffer level and does not rely on any operating system and terminal equipment.It is for this reason that VNC can cross-platform,but VNC's insufficient support for video streaming has become its weakness,and VNC does not support audio.These have little impact on people who only use VNC to work,but with the continuous development of multimedia,people are not satisfied with using private clouds to work,and the shortcomings of VNC have gradually attracted people's attention.This thesis will modify VNC to make it satisfied with the transmission of multimedia and make up for the shortcomings of VNC.The specific idea is to add audio and video modes without affecting the original VNC office mode.In audio and video mode,add audio functions,and use VNC-friendly audio and video compression algorithms such as JPEG2000 video compression algorithm and Opus audio compression algorithm to compress and transmit them,and optimize network communications to enable them to handle large amounts of network data.Of course,After optimizing video and adding audio functions,in order to improve user experience,this thesis will implement audio and video synchronization.For the synchronization problem,the synchronization method that uses the timestamp as the reference object is adopted here.To synchronize audio and video,increase the buffer to reduce the internal transmission delay of audio and video,and increase the feedback adjustment function to adjust the sending rate of the VNC server based on the predicted network bandwidth to ensure the data continuity and reduce network latency for audio and video.For the synchronization problem during audio and video playback,an audio-based synchronization playback algorithm will be proposed here to implement the synchronization problem during audio and video playback.These are the problems solved in this thesis in audio and video mode.Since here are divided into non-audio and video mode,that is,VNC mode and audio and video mode,the mode detection will be essential.The mode detection of this system will be based on The screen changes to determine which mode should be in the current mode,and the mode is changed.Here,the method of screen pixel sampling is used for judgment.By optimizing the VNC protocol,it can perform audio and video transmission to meet the needs of people using multimedia,while retaining the original cross-platform characteristics of VNC,so that people can use VNC for leisure and entertainment in the office. |
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